This invention relates to the detection of proteins by the utilization of the phenomenon by which such proteins interact specifically either immunologically or non-immunologically.
The preparation and use of protein-coated droplets dispersed in a tissue culture medium for growing cells is described and claimed in the U.S. patent application Ser. No. 443,311--Giaever and Keese, filed Nov. 23, 1982. This application is incorporated by reference.
The use of small magnetic particles coated with a protein that will interact specifically with a select protein in order to separate such select protein from a solution is disclosed in U.S. Pat. No. 4,018,886--Giaever. Also, the use of small magnetic particles coated with an antibody layer for sorting out and separating select viruses, bacteria and other cells from multi-cell, bacteria or virus populations is disclosed in U.S. Pat. No. 3,970,518--Giaever.
The use of inert molecules as "spacers" for molecules of interest is described in pending U.S. patent application Ser. No. 358,219--Giaever, filed Mar. 15, 1982 and assigned to the assignee of the instant application.
The preparation of tagged biological particles is described in U.S. Pat. No. 4,041,146--Giaever.
Fluorescent tagging is the preferred mode of tagging. The procedure for fluorescent tagging as well as radioactive tagging are generally understood by those skilled in the art. Suitable methods for fluorescent tagging of an anchored layer of biological particles are thoroughly described in the aforementioned Handbook of Experimental Immunology in Chapter 18 "Immunofluorescence" by G. D. Johnson and E. J. Holborow.
Suitable methods for the radioactive tagging of biological particles are described in Principles of Competitive Protein-Binding Assays [Ed. W. D. Odell & W. H. Daughaday, Philadelphia: Lippincott (1971)] in chapter X "Radioiodination of Peptide Hormones: Procedure and Problems" by F. C. Greenwood pp. 288-296. Another reference work which describes suitable radioactive tagging methods is in Radioimmunoassay Methods [Ed. K. E. Kirkham & W. M. Hunter. Churchill: Livingstone (1971)] "The Preparation and Assessment of Iodinated Antigens" by W. M. Hunter pp. 3-23 and "The Immuradiometric Assay" by G. M. Addison and C. N. Hales pp. 447-461.
These teachings are incorporated by reference as they are representative of the methods useful for tagging biological particles employed in the practice of the invention disclosed herein.
U.S. patent application Ser. No. 665,867--Giaever and Keese, filed Oct. 29, 1984, discloses and claims an invention in which small liquid droplets, coated with a protein that will interact specifically with a select protein, are contacted with a liquid sample to determine the presence or absence of the select protein therein depending upon whether the droplets agglutinate. This application is assigned to the assignee of this inventon and is incorporated by reference.
A common test for pregnancy involves coating small polystyrene latex spheres with the hormone, human chorionic gonadotropin (HCG). When a woman becomes pregnant, the level of HCG in the urine increases significantly. This is an indirect test in which a quantity (as determined by titer by an established procedure) of antibodies to HCG is added to a sample of female urine and is allowed to incubate for from about 5 to about 10 minutes therein. Next, HCG-covered latex spheres are mixed with the urine and the mix is allowed to incubate for from about 5 to about 10 minutes. If agglutination of the spheres takes place, the urine does not contain HCG to the level establishing a pregnant condition; if the spheres remain in single suspension, HCG was present beyond that level.
These tests can be generalized to detect any antigen or antibody. The fact of agglutination preferably should be visible to the ordinary observer.